Technical Field
The present invention relates generally to lighting systems and egress path lighting and deals more particularly with a distributed emergency lighting system having self-diagnostic testing.
It is known to provide emergency guidance systems and emergency lights in buildings. Such prior art lighting systems shown, for example in FIG. 2, are typically centralized and are often characterized by the presence of a spotlight or pair of spotlights 200, also commonly referred to as xe2x80x9cbug eyesxe2x80x9d that are mounted toward the ceiling on a wall 202 and contain a battery 204 which is rechargeable from an AC supply. On loss of power or receipt of other external input signal, the emergency lights throughout the building illuminate.
UL 924 and UL 1994 dictate the code requirements for emergency lighting and path marking systems. These UL standards specify light intensity at the floor level and automatic triggering in response to an emergency situation. Currently employed triggering sources for buildings that require emergency lighting systems is extremely costly to install and maintain. Use-restricted or dedicated electrical power circuits serve the emergency lighting systems exclusively and cannot be used for general lighting. Major battery backup systems are often required to provide electrical power to the restricted circuits of centralized emergency lighting systems in the event of a power failure. In the event of a power failure, which may be localized to one portion of a building, the emergency lighting system responds to serve the entire building. It is also very difficult to retrofit existing buildings with the emergency lighting systems due to the installation costs and the difficulties in rewiring existing structures with dedicated and restricted circuits.
A further drawback with known emergency lighting systems is the inability to assure that the emergency lighting will be active and capable of providing illumination in response to an emergency condition. Typically, known emergency systems require inspection by a fire marshal or other building inspector on a periodic basis to insure the adequacy and integrity of the lighting system. It is well known that the number of inspectors available to perform such inspections is limited and consequently reinspection of an emergency lighting system may not occur on a regular basis if at all. Infrequent, incomplete or missed inspections present a threat to safety, and numerous recorded instances show that the lack of inspection has resulted in untimely deaths and injuries due to fires.
Even in instances when inspections are made, the location of the bug eye lights are such that the inspectors cannot reach them to activate the testing buttons which must be maintained in a operated position for upwards of an hour to two hours to test the battery reserve. Consequently, a number of the emergency lighting systems are not fully tested for code compliance and reliable operation.
The present invention provides a distributed emergency lighting system with a triggering mechanism in the form of an alarm, smoke detector, or other sensor or loss of AC power at the light switch or circuit breaker that controls power to the general lighting within an associated room, corridor or other building area. Both the switch and the circuit breaker have a voltage on the input line side whether the lights in the given area are on or off. The line side of the switch or circuit breaker is monitored for the presence of voltage, and in the event of a voltage failure, the emergency lighting system provides illumination in accordance with code requirements within the associated room or area that has lost its power rather than the entire building.
The present invention also monitors and maintains an emergency lighting system in a unique manner. In limited lighting area embodiments of the invention, each time a light switch, circuit breaker or other power control device is operated to power to the lighting in the room or area to be lit, the emergency lighting system is tested for the length of time that the switch is in the operative position for the area that is required by code to have the emergency lighting. In larger lighting area embodiments, such as entire floors of a building, the emergency lighting system is automatically tested in accordance with a code compliant testing schedule. The code requirements and standards for conditions that satisfy the code requirements such as the battery capacity level, the ability for the system to maintain the intended battery load for the code-specified time and other requirements are integrated into a single system with self-diagnostic testing. In the event the system fails to pass the self-diagnostic tests, an alerting signal or alarm is provided to has some problem and will not properly operate in an emergency mode. The alarm can take the form of the emergency lights in the area not coming on, coming on partially, or coming on in a flashing pattern to alert the user that the emergency lighting system has a problem that requires immediate attention.
In a first aspect of the invention, a distributed emergency building lighting system comprises an electroluminescent (EL) panel, means for providing electrical power to illuminate the EL panel and a control circuit electrically coupled to the electrical power source and the EL panel to illuminate a predetermined designated area within the building in response to an input stimulus such as for example, a pull fire alarm, smoke detector, commercial power failure and the like.
Preferably, the illuminated predetermined designated area further comprises low-level path marking to provide visual delineation of the path of egress.
Preferably, the illuminated predetermined designated area further comprises floor illumination within a prescribed distance from at least one wall of a room in accordance with code requirements.
Preferably, the EL panel is a stripe of indeterminate length located in one or more designated areas including on a floor and on a wall at or near the floor in accordance with code requirements.
Preferably, the EL panel is an exit sign at or near floor level.
Preferably, the electrical power source is an EL power supply and has an input coupled to the line side of an electrical switch supplying commercial AC power to the conventional lighting located in the designated area and to a DC voltage source in the absence of AC voltage at the line side of the electrical switch.
Preferably, the EL power supply includes means for adjusting the light intensity of the EL panel to a desired intensity.
Preferably, the control circuit includes self-diagnostic testing means for verifying operational conditions of the lighting system including the detection of an electrical short circuit and an electrical open circuit of an EL panel coupled to the control circuit.
Preferably, the self-diagnostic testing means includes means for determining normal circuit operation.
Preferably, the self-diagnostic testing means includes means for determining an inoperative EL power supply.
Preferably, the self-diagnostic testing means includes testing means for determining the charge capacity of the battery.
Preferably, the battery testing means includes means for connecting a test electrical load to the battery for a predetermined short time interval; means for sensing the battery voltage during the short time interval that the test electrical load is connected, and means for providing an alarm indication in response to the battery voltage falling below a predetermined voltage value during the voltage sensing time interval.
Preferably, the system includes means for activating the self-diagnostic testing means in accordance with a predetermined time schedule or manually activating the self-diagnostic testing means.
Preferably, the self-diagnostic testing means is activated in response to turning the conventional lighting located in the designated area on and off.
Accordingly, it is an object of the present invention to provide a distributed emergency lighting system that can be retrofitted into existing buildings.
It is a further object of the present invention to provide an emergency lighting system that is small and compact and contains self-diagnostic testing to verify code compliance requirements.
It is a further object of the present invention to provide an emergency lighting system that provides a visual indication to a user that one or more diagnostic tests have failed and require immediate attention.
It is a further object of the present invention to provide an emergency lighting system which also provides emergency egress path lighting.
It is a further object of the present invention to provide an emergency lighting system that includes automatic testing of the system at pre-selected times regardless of the operation of the light switch or circuit breaker that provides power to the lighting system.
It is a further object of the present invention to provide an emergency lighting system that can also be used for theater aisle lighting to provide emergency lighting, egress lighting or general lighting.
It is a further object of the present invention to provide an emergency lighting system that can be interfaced from a control panel.